Solange Knowles attacked Jay Z because of Rachel Roy

Solange Knowles beat up brother-in-law Jay Z because he was being a bit too attentive to designer Rachel Roy at the Met Gala after-party on May 5, according to the New York Daily News.

Geez. Instead of Dobermans, they should have Solange patrolling the fence at Casa Carter

Before Knowles started whaling on Beyonce's husband in an elevator, she reportedly yelled at Roy to keep her distance, sources said.

Knowles, 27, reportedly told the designer, "Anyone who gets close to Jay has to be warned and deal with her as a sister," a source told US Magazine.

The rapper then told Knowles she was "out of line" for mouthing off to Roy.

That, obviously, was not the correct strategy. A source told the Daily News that triggered Knowles' protective side.

"Rachel is a little too close to Jay Z," the source said. "Solange doesn't like it, and Beyonce doesn't like it."

Roy used to be married to Damon Dash, Jay Z's former business partner.

Dash took to Instagram to stick up for Solange, calling her a unique soul. "I am actually impressed with her independent spirit, she seems like a fighter," he said.

Seems?

Roy reportedly didn't respond well when Knowles told her she was "too close" to Jay Z, a source close to the scene said.

"Rachel is combative and a tough girl, she didn't back down," the source said.

Both Beyonce and Jay Z tried to intervene between Roy and Knowles at the Boom Boom room at The Standard hotel, and the three singers decided to leave. That's when the beatdown was captured on a video camera in the elevator.